Difference between revisions of "SMILA/Documentation/HowTo/How to integrate the HelloWorld webservice as a Pipelet"

Revision as of 09:32, 26 September 2008

This tutorial illustrates all steps that need to be performed in order to integrate the HelloWorld webservice as a Pipelet in SMILA

Preparations

It may be helpful to first take a look at the SMILA Development_Guidelines as many topics that are beyond the scope of this tutorial are illustrated there in detail.

Create a new Bundle

• First you have to create a new bundle that will contain the Pipelet. Please follow the instructions on How to create a bundle and use the following settings:

Project name: org.eclipse.smila.sample.pipelet
Plug-in ID: org.eclipse.smila.sample.pipelet
Plug-in Version: 1.0.0
Plug-in Name: Sample Pipelet Bundle
Plug-in Provider: your name or company

• Then you have to integrate your new bundle into the SMILA build process. Therefore please follow the instructions on How to integrate new bundle into build process.
• Edit file META-INF/MANIFEST.MF and add the following import-package dependencies as those are required to implement the basic functionalities of your Pipelet:

Import-Package: org.eclipse.smila.blackboard.BlackboardService;version="0.5.0"
org.eclipse.smila.datamodel.id.Id;version="0.5.0"
org.eclipse.smila.processing.ProcessingException;version="0.5.0"
org.eclipse.smila.processing.SimplePipelet;version="0.5.0"
org.eclipse.smila.processing.configuration.PipeletConfiguration;version="0.5.0"

• In order for the PipeletTrackerService to detect your new Pipelet you have to add the following line to file META-INF/MANIFEST.MF to register the class that will implement your SMILA Pipelet:

SMILA-Pipelets: org.eclipse.smila.sample.pipelet.HelloWorldPipelet

Create Java classes from WSDL

comming soon ...

Implementation

• create a package org.eclipse.smila.sample.pipelet and a Java class HelloWorldPipelet
• use the following code as a template for your new class (for your conveninace you may also download the complete source file HelloWorldPipelet.java)

package org.eclipse.smila.sample.pipelet
 
import org.eclipse.smila.blackboard.BlackboardService;
import org.eclipse.smila.datamodel.id.Id;
import org.eclipse.smila.processing.ProcessingException;
import org.eclipse.smila.processing.SimplePipelet;
import org.eclipse.smila.processing.configuration.PipeletConfiguration;
 
public class HelloWorldPipelet implements SimplePipelet {
 
  public HelloWorldPipelet(){
  }
 
  public void configure(PipeletConfiguration configuration) throws ProcessingException {
    // read the configuration properties
  }
 
  public Id[] process(BlackboardService blackboard, Id[] recordIds) throws ProcessingException {
    // process the recordIds and create a result
  }
}

Read PipeletConfiguration

• first let's create two member variables that store the names of the in- and output Attributes as well as String constants for the property names used in the configuration

private final String PROP_IN_ATT_NAME= "IN_ATT_NAME";
private final String PROP_OUT_ATT_NAME= "OUT_ATT_NAME";
 
private String _inAttName;
private String _outAttName;

• then we will fill those members with the Attribute names provided by the PipeletConfiguration in method configure(PipeletConfiguration configuration). The method getPropertyFirstValueNotNull(String) will check that the value of the property is not null. If it is null a ProcessingException will be thrown. In addition we should ensure, that the provided String is not empty or consists only of whitespaces.

public void configure(PipeletConfiguration configuration) throws ProcessingException {
    _inAttName = (String) configuration.getPropertyFirstValueNotNull(PROP_IN_ATT_NAME);
    if (_elementId.trim().length() == 0) {
        throw new ProcessingException("Property " + PROP_IN_ATT_NAME + " must not be an empty String");
    }
 
    _outAttName = (String) configuration.getPropertyFirstValueNotNull(OUT_ATT_NAME);
    if (_elementId.trim().length() == 0) {
        throw new ProcessingException("Property " + OUT_ATT_NAME + " must not be an empty String");
    }
}

Read Input Data

comming soon ...

Process Input Data

comming soon ...

Write Output Data

comming soon ...

Configuration and Invocation in BPEL

In this sample we will integrate the HelloWorldPipelet in the SMILA indexing process just before the Record is stored in the Lucene index. With this configuration the input for the HelloWorldPipelet will be read from Attribute Title and the modified output will be stored in the same Attribute, overwriting the previous value.

• edit file configuration\org.eclipse.eilf.processing.bpel\pipelines\addpipeline.bpel and add the following right between <extensionActivity name="convertDocument"> and <extensionActivity name="invokeLuceneService">

<extensionActivity name="invokeHelloWorldPipelet">
    <proc:invokePipelet>
        <proc:pipelet class="org.eclipse.smila.sample.pipelet.HelloWorldPipelet" />
        <proc:variables input="request" output="result" />
        <proc:PipeletConfiguration>
            <proc:Property name="IN_ATT_NAME">
                <proc:Value>Title</proc:Value>
            </proc:Property>
            <proc:Property name="OUT_ATT_NAME">
                <proc:Value>Title</proc:Value>
            </proc:Property>
        </proc:PipeletConfiguration>       
    </proc:invokePipelet>
</extensionActivity>

Test your Pipelet

comming soon ...